The present invention relates to temperature control systems for vehicles, for example air conditioning systems for railway carriages.
There is an increasing demand for the air conditioning of railway carriages in order to improve passenger comfort. In view of the very substantial number of carriages in operation and the long life of such carriages, it is essential that any such system must be comparatively inexpensive and with a reasonable life expectancy and easy maintenance.
There have previously been two main proposals for air conditioning such carriages In one proposal, a complete air-cooled air conditioning unit is slung beneath a floor of the carriage in the ambient air and the cooled air produced by the system is ducted into the carriage. This system has the disadvantage, however, that the necessary air ducting is bulky and expensive to install.
A second previously proposed system mounts a refrigerating circuit of the air conditioning system on the roof of the carriage within the space to be cooled. The refrigerant is then led by pipes to a refrigerant/air heat exchanger slung beneath the floor of the carriage in the ambient air. This arrangement has the disadvantage that the refrigerant must be conveyed by pipes between the roof and the floor of the carriage. There is a strong possibility that, in time, refrigerant will leak from these pipes and such leaks, in view of the refrigerants currently used, have an adverse effect on the environment. In addition, such leaks are difficult to trace and repair.
The present invention seeks to overcome or reduce one or more of the above disadvantages.